h115i platinum with LL Fans

so my whole rig is kitted with LL fans, looks are important , so i want to change my 240 rad that currently has 2 LL 120 on them, with a H115 platinum 280 (i have 2 more LL 140 fans) now i know the ML fans that come stock with the H115 go up to 2000 rpm, and the 140 LL fans are some what limited to 1400RPM tops, im cooling an OC 8700K 4,8ghz all cores, my question is, are the LL fans at 1400RPM enough for cooling, i do intend to still use the ML fans outside of the top of the case (680x) as pull configuration, at about 200-300 rpm slower than the LL fans

They are enough by themselves. You can't out-watt a 8700K at any setting on a 280mm radiator. Even at the extreme you will top out around 180W and that isn't that much to dissipate. At 300W I could get a 2-3C difference between ML and LL at the same speed, but you will average less than half that and I would expect the difference to be about 1C.

so no problem using the LL 140s at 1350RPM ?

one day i do intend to use this radiator with a 10700K or 10900K

No, your good at 1350. I usually capped it at 1200-1300 rpm.

 

Lots of reviews out for 10900K with the words “excessive heat” in the title. I did see one where they talked about it “overwhelming their 280mm AIO”. I would say that is a slight embellishment when the coolant delta is 15C, but the cpu voltage rise is 50-60C. Nevertheless, if you run synthetic benchmarks all day or other heavy AVX instruction programs, you might need more than 280mm cooler for an overclocked 10900K. That would be close to 300W and you would be up near a 40C coolant temperature no matter what fans you use.